Battery/ EV Kits

I'm not sure any existing mod can exceed the 35MPH limit, but I'm sure the extra batteries to go 30 miles would weigh a lot unless technology changes we've heard about show up for sale....

 

Without tremedous weight, you would need lithium I suppose. NIMH would work only if you had "lots" of them.
For 12 grand you can get set up to do what your talking about.. maybe in a few years it will be much cheaper.
http://calcars.org/priusplus.html
http://calcars.org/priusplusfactsheet-v1.10.pdf
http://www.katu.com/consumernews/story.asp?ID=79020
http://www.peve.panasonic.co.jp/catalog/e_kaku.html

I still think the most practicle cheapest consideration is to just get a couple more NiMH batteries from wrecked cars and wire them in parallel...
Be care that all the batteries are of equal age... or the weakest will drag the others down to its level.

 

You'll be wanting a plug-in Prius then. However the EDrive conversion mentioned above (which gives about 50-60 miles electric assist at ~120-150 mpg) will set you back about $12,000.

Frankly, that's still far too expensive and for this reason a lot of people are, like you, considering building their own. You'll likely not manage to escape the low-speed EV mode limits, but you will be able to benefit from "electric-assist" at all speeds, which reduces fuel consumption to between zero and a third of what you would normally use (well, until the battery is depleted anyway).

Nevertheless 30 miles in <30 mph EV mode would equate to approximately 6 kilowatt-hours battery storage required. That amount of energy can be contained in 680 individual 18650 sized lithium-ion batteries. Wholesale, these are about $3 each, so you'd be looking at about $2,000 for the batteries themselves. Of course the bigger challenge will be wiring them all up together in a safe, monitored way. AC propulsion are the experts at this, having made packs like this for several applications. Each cell weighs 44 grammes, so the batteries themselves would add 30 kg weight to the car. If only there was a kit out there for the DIYer to do the same....

Steve Lapp has already managed to work out how to store energy in a secondary battery (he used a small 12V lead acid) and then inject it slowly into the Prius HV battery to reduce gasoline consumption, so that part of it shouldn't be too difficult.

To chat with other folk thinking along the same lines, you may wish to try these links:

http://autos.groups.yahoo.com/group/gridable-hybrids/

http://www.seattleeva.org/wiki/EAA-PHEV

Tell us how it goes!

 

Of course, the speed limit for EV mode in Europe is somewhat lower - you can't exceed 30mph indicated, which is probably more like 27mph actual. So it sounds like you US folks who've fitted EV buttons are flogging the thing harder than us.

 

Hi SJ,
As far as going over 35mph is concerned, the reason you can't is so that the electric motor doesnt over rev, it is limited to 3000rpm, so I imagine there is no modding that unless you redesign the whole electric motor drive.

I too am considering adding extra cells to my Gen2 and would like to find out some more info on what signals will delay turning the petrol motor on after the electric motor has been running for a while.
Does it switch to petrol motor simply because the battery has run down to a predetermined point, or does the power control unit monitor the KWhr output of the battery and then call upon the petrol motor once the battery has reached a set state of charge.
And then the question has to be asked....Will the onboard generator be able to charge the extra cells I have in parallel with the original battery pack? If not will I have to add a charger (and then it becomes a "plug in" hybrid, which I also dont have a problem with).

Any info to shed some light on how this would be acheived (or at least evolved towards) is greatly appreciated.

 

The EV switch is an easy mod. See the Knowledge Base for a DIY, or buy the kit from Costal.

HOWEVER, when you start messing with the batteries you are getting into some very serious and dangerous stuff. This is not an amateur mod. Unless you are a professional electrical engineer, and willing to risk serious damage to yourself and your car, I would strongly advise against doing anything with or to the HV batteries. There are many issues and considerations involving matching battery specs, cooling, and compatibility with the car's computers.

 

Daniel.. I have made several inquiries along those lines and have never gotten concrete responses..
I know the computer monitors "each cell" of the factory battery, but I have heard of folks wiring in parallel with a similiar bank or even quite different without negative repercussions...
However they never really spelled out whether they had to mod the computer in any way..

I am still under the influence that if one was to buy a brand new battery bank similiar to the factory in the beginning of a purchase, that the batteries would be matched and therefore would not drain or pull from each other?

If fact.. I don't know why 3 banks would not hurt?.. that would increase AH from 6.5 to 19.5?
Here is one similiar link that I'm sure you have already studied, but I will post it for the benifit of others and to gender questions.
http://privatenrg.com/PriusBattery.htm#2004Ah%20work

 

Windstrings: I stand by what I said: This mod works, and improves mileage, but is not a mod for the casual amateur. Consider just a few comments from the page you cite in your last post:

"This was tricky because of needing to massage the HV Batt ECU data that was going to the HV ECU."

He does not specify what "massage the HV ECU data" means, but I have read elsewhere that the computer needs to be tricked into accepting data that seems contradictory to it because of the added battery capacity. The computer knows the capacity of the battery, and is not happy if it does not respond to charging and discharging the way a battery of that capacity would. These guys have figured out how to address that problem, but it is not trivial. You gotta really know what you are doing.

"Just a few weeks later I had gotten hold of 2002 Prius battery which ran at 300 Volts so I had to take off 10 modules, cut the box, rewire the buss bars, rewire SMR1 & SMR2 and redo the cooling. I had decided to do a PbA & NiMH install with some unusual logic to control it all & it worked!"

Note the term above: "unusual logic." He was doing something to the processing of data. He does not say what. Custom-programmed chips tied into the car's own computers???

He uses thermostatically-controlled fans, and he appears to have removed the spare tire. He also mentions an issue of lubrication of the PSD. He says he's had no problems with it, but also that without the added pump it's important to limit the amount of time in EV mode. Also, he does not say there what the whole conversion costs, though I imagine they may have that on their main site.

As proof of concept, this is brilliant. But it is not a project for the backyard tinkerer.

I think what this guy is doing is great. I want a car like that. But I want it built by Toyota, covered under warranty, and I do not want to have to trade my spare tire for the added capacity.

Actually, the only thing I have against the Prius-Plus concept is that I suspect (and deeply hope) that Toyota will do all of this long before these folks could make it commercially viable. But I still think they are great, for providing the proof of concept and the real-world data.

 

The link in Windstrings' post led me to this very interesting link:

http://www.edrivesystems.com/Edrive-FAQ.html

This outfit is a commercial company promising to offer a plug-in-hybrid conversion for the 2004/2005/2006 Prius at an anticipated price of about $12,000. It will be installed ONLY by their own technicians, due to the safety issues of working with high voltage, and the sensitive nature of the electronics.

They claim an EV range on a full battery charge of 50 to 60 miles, but only if you stay within the Prius's EV limits. (I.e., under 34 mph, no hard acceleration, no heater demand, etc.) Otherwise, the engine and MGs will work together, as the Prius is basically designed to do, but with significant electrical input, greatly improving mileage.

They throw out some fabulous miles numbers, but stress those are gasoline usage numbers, i.e., not counting the electricity used from the grid. But they point out that grid electricity is a lot cheaper than gas.

Plug your car in at night, and greatly increase your mileage. Forget to plug it in, and get the same mileage as the Prius would get without the conversion (but with an extra 180 pounds of cargo, for the difference between the OEM battery and the big one that replaces it.)

This is very cool. I hope Toyota does something like this in 2008.

 

Thanks Daniel for pointing out the items of condsideration.

Indeed I look with envy at his project!....It just makes me salivate all over the place! :lol: It looks like a beautiful job!.... It makes we want to try and tackle it, since I have built a hydroelectric system that has been working for about 20 years now, I tend to think I could do it quite easily...

But your right, the part that intimidates me is the Computer stuff.
I sure wish I could talk to him myself?..... Ill have to try and make one of those shows where the strut thier stuff!

It sure seems like simply increasing the batt size and keeping the voltage the same would normally be a very simple mod... but when you start playing with the onboard computer, that really changes the simpicity of things!

I don't know if your burn't out on reading or if you have already read this.. but here are some facinating writeups on projects already accomplished.
http://calcars.org/priusplusfactsheet-v1.11.pdf
http://calcars.org/priusplus.html

Its really fun and facinating technology....... I want to play.. I want to play! :angry:

Ill be anxiously waiting till these mod prices come down.